This invention relates to a hollow pole made up of a core of wood strips that are glued along mating edges and forming an enclosure around a central axis, with one or more layers of high strength veneer tightly wrapped and glued to the exterior of the core to provide a high strength pole. Power companies that require poles have tried to find a satisfactory substitute for a solid wood pole. Trees that will provide a long, solid pole are becoming unavailable and that means that costs are increasing. Likewise, more efficient use of wood has been recognized as a way of obtaining greater strength than a solid wood pole of similar dimensions.
Several efforts have been made to make a suitable hollow wood pole that is formed with a plurality of staves or strips that are glued together along their mating side edge surfaces around a central axis. For example, a hollow, wood stave pole made by using vacuum on the interior during gluing is shown in U.S. Pat. No. 4,468,273. Sealing caps are used for sealing the ends of the hollow pole so the interior vacuum can be created for gluing.
U.S. Pat. No. 4,428,792 shows a column made up of preformed multiple layers of glued veneer panels that can be wrapped around a solid core of wood. International publication WO80/02709 also shows a multiple stave, glued pole.
Other patents of general interest show pole structures that are hollow, such as the pole structure in U.S. Pat. No. 3,200,554 and a column used for construction shown in U.S. Pat. No. 4,387,546, which is similar to U.S. Pat. No. 4,428,792. Another pipe shaped structure is shown in U.S. Pat. No. 4,897,140.
U.S. Pat. No. 5,150,557 shows a column that is formed of two sections glued together. However, none of the patents illustrate a hollow stave pole core having a high strength, permanently mounted overwrap at the outer periphery, where the greatest contribution to bending strength is achieved.